Method and apparatus for making a light weight container

ABSTRACT

An improved lightweight container incorporates a thinner wall structure in an essentially octagonal container having a bottom member, a plurality of sidewalls, a spout, an upwardly converging neck member coupling the sidewalls of the spout, a handle molded into the container and a radiused transiting section between the sidewalls and the spout which eliminates weakened corner sections and improves overall strength to weight ratios.

RELATED U.S. APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/405,495 filed Feb. 27, 2012, which claims the benefit of U.S.Provisional Application No. 61/466,588 filed Mar. 23, 2011.

FIELD OF THE INVENTION

The present invention relates to containers for storage of liquids,granular materials and the like, and methods and apparatuses for formingthe same. More particularly, the container of the present invention is asingle piece blow-molded plastic container formed in a multi-sidedconfiguration with modified corner radii, utilizing a smaller volume ofraw material to obtain volumes and strength equivalent to the prior art.

DESCRIPTION OF THE RELATED ART

Blow-molded plastic bottles are well known for use for holding a widevariety of liquids such as milk, water and juice. The same types ofcontainers may be used for granular materials. Containers of this typeare manufactured in a variety of sizes, conventionally formed of avariety of thermoplastic materials.

Typical of these containers are those disclosed in U.S. Pat. No.6,527,133, issued to McCollum et al.; U.S. Pat. No. 4,805,793, issued toBrandt et al.; and U.S. Pat. No. 6,237,792, issued to Skolnicki et al.

Containers of this type are relatively thin-walled, and are generallysquare or rectangular in cross-section, feature a molded handle, andtypically have a finished weight of over 60 grams. Such weight ofmaterial is essential to maintaining sufficient strength for thecontainer to withstand the industrial filling process, in particular,the loads imposed for securement of a closure, such as a cap, lid orscrew top to the spout on the top of the container. FIGS. 1A, 1B, 1C and1D show top, front, side and bottom views, respectively of blow-moldedcontainers formed according to the prior art. The typical prior artcontainer is depicted in FIGS. 1A-1D incorporates a top 102, a bottom104 and spout 120. Top 102 and bottom 104 are interconnected bysidewalls 106, and includes a handle 122. In the prior art, a relativelyacute transition occurs at the top corner 130 of the top 102 of thecontainer, where the top 102 joins the lower circumference of the spout120. Then, when the top 102 joins the sidewall 106, a second relativeabrupt transition occurs at upper corner 124, generating a comparativelysharp angle between the top 102 and the sidewall 106. Transitioning tothe bottom section of the prior art container, a first intermediatecorner 126 creates a first transition between the sidewall 106 and thebottom 128 of the container. A bottom corner 128 completes thetransition between the sidewall 106 and bottom 104. The combination ofthe corner transitions at intermediate corner 126 and bottom 128,coupled with the substantial distance between intermediate corners 126and 128 demand a substantial distribution of material to the bottomsection of the container to provide the necessary strength. The sameproblem is evident at the top of the container 102, where the top 102 ofthe container joins the sidewall 106 at upper corner 124. These multiplespaced apart transitions often result in excessively thin walls at thetransitions, thereby weakening the container.

More recently, containers have been created which incorporate ribs andother design features in the upper sidewalls of the container toincrease mechanical strength, well at the same time decreasing the wallthickness of the finished container. By reducing the overall thicknessof the container, substantial savings in materials cost can be realized.Newer containers utilizing these design methodologies have resulted inreductions in material required for each container, and correspondingreductions in material cost, of between five and seven percent. Suchreductions in the typical production environment can result insubstantial cost savings over time.

The existing containers, however, suffer from important limitations.Particularly, as known in the prior art, the manufacture of thin-walledthermoplastic containers utilizing the blow-molding techniques cancreate unacceptably thin wall dimensions near the top and bottom of thecontainers, where the tops and bottoms of the containers join the sidewalls. Excessive thinning in these areas weakens the overall containerand reduces its ability to withstand the forces typically imposed duringthe filling process. To insure that sufficient wall thickness remains inthese vital sections, the current containers require a minimum ofapproximately fifty-eight to sixty grams in weight. A need exists,therefore, for a container design and method of manufacture, whichpermits more even distribution of thermoplastic material throughout thewall of the container, while allowing significant reductions in theamount of material required to produce the container.

SUMMARY OF THE INVENTION

In summary, a thin-walled container in accordance with the presentinvention is formed having sidewalls, a bottom, a top having a neck, ahandle, and a spout. The container has eight sides, and a smoothlytapered radius between the spout and the sidewall. To form thecontainer, specialized round tooling is utilized in the die and itsassociated mandrel to achieve more even distribution of thethermoplastic material during the molding process. The resultingcontainer displays a more efficient distribution of the materials alongthe sidewalls, top and bottom of the container, typically at a weight offifty-two grams or less.

It is an object of the present invention, therefore, to provide athin-walled container having an extremely light weight. Further, it isan object of the present invention to provide a thin-walled containerhaving six or more sides and a specially radiused transition between thespout and sidewall of the container.

It is another object of the present invention to position the handle ofthe container to improve venting of the interior of the container duringthe pouring process.

It is another object of the present invention to provide a system formanufacturing the same volume of container as taught in the prior art,while maintaining the necessary structural integrity of the container towithstand the industrial filling process.

It is a further object of the present invention to provide and improvedcontainer having the same volume and fitting in the same standard caseas taught in the prior art.

These, and other objects of the invention, will be apparent from theassociated drawings and description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A us a top view of a prior art container, constructed according tothe methods of the prior art.

FIG. 1B is a front view of a prior art container, constructed accordingto the methods of the prior art.

FIG. 1C is a side view of a prior art container, constructed accordingto the methods of the prior art.

FIG. 1D is a bottom view of a prior art container, constructed accordingto the methods of the prior art.

FIG. 2A is a front view of a first embodiment of the present invention.

FIG. 2B is a side view of a first embodiment of the present invention.

FIG. 2C is a bottom view of a first embodiment of the present invention.

FIG. 2D is an alternate bottom view of a current embodiment of thepresent invention.

FIG. 2E is an additional bottom view of another variant of a currentembodiment of the present invention.

FIG. 3A is a front view of the present invention.

FIG. 3B is a side view of another embodiment of the present invention.

FIG. 3C is a top view of another embodiment of the present invention.

FIG. 3D is a bottom view of another embodiment of the present invention.

FIG. 4 is a diagram showing a die and mandrel according to an embodimentof the present invention.

FIG. 5 is a diagram showing a parison and a mold according to anembodiment of the present invention.

FIG. 6 is a top view of embodiments of the present invention held in astandard dairy crate.

FIG. 7A is a top view of an embodiment of the present invention;

FIG. 7B is a side view of an embodiment of the present invention;

FIG. 7C is a side view of an embodiment of the present invention;

DESCRIPTION OF THE PREFERRED EMBODIMENT

The description which follows will be best appreciated by reference tothe accompanying drawings. Although the invention is described inconjunction with the drawings, and a plurality of preferred embodimentsis described, it will be appreciated that these descriptions are notintended to limit the invention to those embodiments. The inventionincludes a variety of alternatives, modifications and equivalents whichmay be included within the spirit and scope of the invention as definedby the appended claims.

The invention will be better understood by a full appreciation of theprocess of manufacture typically used in the art. A conventionalblow-molding machine includes a loading station where pelletizedthermoplastic material, such as polyethylene, may be introduced into ahopper or feed bin. The hopper, in turn, feeds the pelletized orgranular thermoplastic materials, which is at room temperature, to aheater/drive system. Such a system typically includes a screw driveprovided with one or more heating mechanisms or elements which graduallyraise the temperature of the thermoplastic material to approximately365° F. Once the material has attained this temperature, the materialliquefies and becomes taffy-like in its consistency. The material isthen introduced into the mold through a die and mandrel combination,whereby the thermoplastic material is evenly distributed in the mold.The blob of thermoplastic material which forms as it is extruded throughthe gauged opening between the die and mandrel is called a parison. Oncethe parison is formed the mold is closed around the parison possiblyimparting the general shape of the interior of the mold onto theparison. This aids in distributing the material of the parison evenlythroughout the interior of the mold when the mold is pressurized. Themold is then pressurized via the blow pin thereby forcing the parison toexpand throughout the interior of the walls of the mold, and impartingto the material the finished shape of a container. To facilitate themolding process, the mold walls are cooled to approximately 30° to 40°F., to restore the liquefied thermoplastic material to solid state. Oncethe part has formed, the mold is opened and the part is removed from themold.

Turning now to FIGS. 2A-2E, a first embodiment of a container formedaccording to the present invention is disclosed. Container 10 consistsof a top section 12, a bottom 14 and a plurality of sidewalls. Eightsidewalls alternate in dimension, four being long sidewalls 16 and fourbeing short sidewalls 18. The top section 12 is configured with a spout20 having an opening 21 by which material may be introduced into theinterior of the container 10. The container is molded as a single piece,and includes a handle 22 which is hollow and permits liquid and air topass inside it. Preferably, the handle is configured adjacent to a shortsidewall 18, so that when the container is held for pouring, the centerof mass is concentrated along the axis which intersects both the handleand the opposing short sidewall of the container.

In a first embodiment, the height of the container 10 is measured fromthe bottom of the container to the bottom of the spout is approximately9.231 inches, for a container having a volume of approximately 234 cubicinches, essentially a one-gallon container. In this embodiment, a radiustransition 24 is formed between the upper limit of the sidewalls 16, 18and spout 20. Preferably, the radius R has a dimension of approximatelythree inches, thereby providing a smooth transition between thesidewalls 16, 18 and spout 20 of the container 10 in comparison to theprior art. This area of transition may include one or more ribs 28 toprovide additional strength to the container. The container 10 isblow-molded, and includes a single piece thin wall construction. Thesidewalls, when viewed from above, form a generally octagonalconfiguration as seen in top or bottom plan views. The container 10includes a bottom 14 which is interconnected to the sidewalls 16 and 18and has a plurality of ribs 30. In one example, the radius transition 24in between the sidewalls 16, 18 and the spout 20 has a radius ofapproximately 3″ and a transition section length of about 2.5″ in acontainer having an overall height of approximately 10″.

A second embodiment of the invention as disclosed in FIGS. 3A and 3B,which does not include the ribs 30 but does include the same upperradius transition 24. Containers of either configuration may be formedwith one or more volume control inserts 32 molded into one or more sidesof the container to adjust the total internal volume of the container10.

Turning now to first embodiment of the invention as shown in FIGS. 2A-E,it will be appreciated that the top section 12 of the container 10incorporates an upper radius transition of radius R between the bottomof the spout 20 and the top of sidewalls 16 and 18. The absence of thesharp transitions between the bottom of the spout and the container top,and the top of the sidewall in the container top results in increasedstrength while allowing for even distribution of the thermoplasticmaterial, eliminating the sharp transitions of the prior art. Theinclusion of rib 28 imparts additional strength to this vital section ofthe container.

Likewise, the intermediate corners 34 and bottom corners 36 arepositioned closer than the corresponding transition corners in the priorart, resulting in a more even distribution of the thermoplastic materialat those critical locations. As shown in FIGS. 2C-2E, a variety ofmethods may be adopted for placement of strengthening ribs 30 on thebottom of the container to impart a higher degree of rigidity, utilizinga thinner bottom wall section than required by the prior art. A varietyof planiforms may be selected as depicted in FIGS. 2C-2E, each of whichforms the desired function of imparting the necessary strength to thebottom of the container.

FIGS. 3A-3D show a second embodiment of the invention, where the bottom44 of the container 38 is provided with a plurality of impressions 40,42 which may facilitate stacking of containers 38. FIGS. 3A, B, C and Dshow a first side view, a second side view, a top view and a bottomview, respectively of an embodiment of the invention showing impressions40, 42 cast into the bottom 44 of container 38.

It will be further appreciated that additional strength may be obtainedby multiplying the number of sidewalls as shown in FIGS. 2C and 3C. Ineach of the embodiments therein depicted, it will be appreciated thatthe container has eight sidewalls. The utilization of multiple sidewallsdecreases the angles between the sidewalls, and the gentler radiusestherein incorporated allows for more even distribution of thethermoplastic material during the molding process. Embodiments of thisdisclosure have sidewalls arranged as opposing pairs where the distancebetween pairs of sidewalls is arranged so that two pairs of sidewallsare separated by a first distance and a third pair of sidewalls areseparated by a second distance. The ratio of the first distance to thesecond distance is between about 1:1 to about 1:1.10, with the preferredratio equal to about 1:1.06.

A further advantage of incorporation of the upper radius transition 24is the improved pouring characteristics of the container. In a priorart, the sharp transitions between the top of the container and thespout and the upper part of the handle and the top of the containerresults in periodic difficulty in pouring from the container as liquidblocks movement of the contents of the container away from the handle,causing the contents of the container to pour in spurts, rather than ina continuous stream as air is admitted past the liquid. By utilizationof the extended upper radius transition of the present invention, thecontents of the container flow easily. In addition, the handle sectionis designed to be hollow and allow air to escape during poring due toits proximity to the spout to thereby mitigate splashing as liquid ispoured from the container. It is also noted that the curved nature ofthe upper radius transition between the sidewalls and the spout permitsthe handle to be attached higher on the container proximate to the spoutand have a smaller hole between the handle and the container, therebyimproving the pouring characteristics as mentioned above and permittingthe container to contain a greater volume of material.

Improved characteristics of containers produced according to embodimentsof this invention are due at least in part to improvements to theequipment used to produce the containers, in particular the die andmandrel combination and the shape and size of the mold. FIG. 4 shows across-sectional view of an extrusion mechanism 50 according to anembodiment of this invention. This extrusion mechanism 50 operates aspart of a blow molding machine, where the extrusion mechanism 50positions a circular mandrel 54 having an air passage 56 in a circulardie 60 so that a predetermined die gap 66 exists between the mandrel 54and the die 60 a predetermined die angle 64. Thermoplastic material isforced into the extrusion mechanism 50 in the direction indicated byarrow “A”, flows around the mandrel 54 and through the die gap 66 toform a parison. A parison is typically a hollow tube or bulb ofsemi-molten material which extends past the mandrel into the volumewhich will be the cavity of the mold. Once the desired parison iscreated, the mold (not shown) closes around the parison so that air canbe introduced into the air passage 56 to inflate the parison to fill theenclosing mold. The size and shape of the die angle 64 and die gap 66with respect to the mandrel 54 can determine the exact proportions ofthe parison. In this case the die 60 and mandrel 54 are both circular.The first parameter is the die angle 64 which measures the angle of thedie 60 with respect to the mandrel 54. Die angles 64 can range from 0°to 30° or more particularly about 15°-18°. Using a die angle 64 of lessthan 30° allows the die gap 66 to be smaller. In the case of one galloncontainers, a die gap 66 of between about 0.001″ and about 0.025″ ormore particularly about 0.006″ produces a parison with the desired shapeand size when the appropriate amount of material is forced through thedie/mandrel combination.

In addition to the shape due to the die angle 64 and die gap 66, asshown in FIG. 5, a parison can change shape when the mold is closed.FIG. 5 shows a cross-sectional view of a parison 70 with a hollow core72 inside a mold cavity 74 formed by the two parts of a two-part mold76, 78 according to an embodiment of this invention. The parison 70 haselongated and formed an elliptical shape following closure of the moldhalves 76, 78. Embodiments of this invention use the elliptical shape ofthe parison 70 in combination with improved design of the mold cavity 74to improve the quality of the finished container. By forming a containerwith an elongated or diamond shape, shown in FIG. 5, the walls of themold 88 can be kept at a substantially small similar distance from theparison 70. Replacing corners with short sidewall sections 80, 82, 84and 86 and shaping the mold to mirror the shape of the parison improvesthe structural rigidity of the resulting blow molded container whilemaintaining overall container strength using less material. In addition,this design helps to avoid dented corners as the resulting container isused, thereby enhancing its appearance. The elongated parison 70 fitsthe mold cavity 74 more closely than a mold cavity having four symmetricsides. Shaping the interior of the mold to form an elongated shapesimilar to the parison 70, where the distance from the parison to themold wall 88 is substantially equal causes the parison 70 to mold to theinterior shape of the mold when the interior of the parison ispressurized. Having the interior of the mold closely mirror the elongateshape of the parison will provide the strongest container for the leastamount of material by distributing the material evenly and therebyproviding uniform wall thickness. Typical gallon containers manufacturedby blow molding can use a minimum of 58 grams of thermoplastic materialto form successfully, with 61-64 grams being typical in manufacturingoperations. Embodiments of this invention can manufacture galloncontainers with desirable strength and appearance using less than about55 grams of thermoplastic materials, or more preferably less than about52 grams of thermoplastic material.

FIG. 6 shows a top view of embodiments of this invention held in astandard dairy crate. Dairy crates are cases constructed to holdmultiple containers so that dairy crates with full containers may bestacked without damage to the containers or contents. Dairy crates aremanufactured in standard configurations and it is an advantage ofembodiments of this invention that these embodiments fit in a standarddairy crate. As shown in FIG. 6, a standard 4-gallon dairy crate 51holds four 1-gallon containers 52 made in accordance with embodiments ofthis invention.

FIG. 7A shows a top view an embodiment of this invention with the 6″×6″footprint of the container indicated. FIGS. 7B and 7C show side views ofan embodiment of this invention showing how the container can fit in aspace with height 10.040″. As can be seen from FIGS. 7A, 7B and 7C,containers constructed according to disclosed embodiments can fit in a6″×6″×10.040″ cube. Fill percentage is the percentage of the volume of aminimal enclosing cube that is contained within the container. Disclosedembodiments have a fill percentage greater than about 60%. Moreparticularly, containers constructed according to disclosed embodimentsfill about 64.7% of the 6″×6″×10.040″ cube required to hold a container.Disclosed embodiments provide a fill percentage in excess of 60%, whichpermits more material to be stored in containers in a given volume whilemaintaining ease of use features such as handle placement.

The above-described embodiments have been described in order to alloweasy understanding of the present invention and do not limit the presentinvention. On the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the scope ofthe appended claims, which scope is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructure as is permitted under the law.

What is claimed is:
 1. A method for forming a blow-molded containercomprising: providing a two or more piece mold having a body including:a bottom section for forming the container bottom; sidewall section forforming a plurality of sidewalls; a spout section for forming a spout; aneck section for forming an upwardly converging neck member coupling thesidewalls to the spout having a convex radius transition section ofapproximately three inches in a container having an overall height ofapproximately ten inches; a die having an annular opening; a hollowmandrel positioned within the die annular opening so the opening betweenthe die annular opening and the mandrel has a gap of about 0.006 inchesand an angle of about 15°-18°; forming a parison by introducing athermoplastic material in liquefied form through the opening between thedie and the mandrel; moving said mold pieces to a closed positionproximate to the die so the parison assumes an ovoid cross-sectionwhereby the outer surfaces of the parison are positioned approximatelyequidistant from the interior surface of said mold; inflating saidparison though the blow pin thereby bringing said parison into contactwith the interior surfaces of said mold forming a container; permittingsaid container to cool; and, ejecting said container from said mold. 2.The method of claim 1 further comprising said container having a weightof less than about 55 grams of thermoplastic material for a one galloncontainer.
 3. The method of claim 1 wherein said sidewall sectionfurther comprises long sidewalls and short sidewalls where a first pairof sidewalls are spaced apart by a first dimension and a second pair ofsidewalls are spaced apart by a second dimension where the ratio of thefirst dimension to the second dimension is about 1:1.06.
 4. The methodof claim 1 further comprising: molding a handle into the containerproximate to the spout.
 5. The method of claim 1 wherein the mold is atwo piece mold.
 6. The method of claim 1 wherein the mold is a threepiece mold.
 7. The method of claim 1 wherein the blow molded containerhas a shape which fits in a standard milk crate.
 8. The method of claim1 wherein the blow molded container has a fill percentage of greaterthan about 64%.
 9. A method for forming a blow molded container, saidcontainer having a length dimension and a width dimension less than saidlength dimension, the method comprising: providing a split mold havingan internal cavity having said length dimension and said width dimensionand a central vertical axis defining a midpoint in said length dimensionand said width dimension; positioning a circular die proximate to saidmold, the center of said die positioned co-axially with said verticalaxis; positioning a circular, hollow mandrel having a central axispositioned co-axially with said die and said vertical axis; spacing saidmandrel from said die to create an annular aperture between said die andsaid mandrel with a spacing of about 0.006 inches or less, having anangle of about 15°-18° in relation to said axis; extruding heatedthermoplastic material through said aperture to form a parison having auniform wall thickness, manipulating said split sections of said mold toa closed position thereby causing said parison to assume an ovoidcross-section, whereby said parison outer surfaces are positionedapproximately equidistant from the interior surfaces of said mold;inflating said parison via said blow pin to expand said parisonuniformly and bring said parson into contact with the interior surfacesof said mold, forming a container of uniform wall thickness; permittingsaid container to cool; and, ejecting said container from said mold. 10.The method of claim 9 further wherein said mold comprises an uppersection, a sidewall section, a spout, a bottom and a handle.
 11. Themethod of claim 10 wherein said upper section comprises a continuousradius transition section between said sidewall and said spout whereinsaid radius is about three inches and said transition section is about2.5 inches in a blow molded container having an overall height of about10 inches.
 12. The method of claim 9 further comprising metering saidheated thermoplastic material is metered to achieve a maximum blowmolded container weight of about 55 grams for a one gallon container.13. The method of claim 9 wherein the blow molded container has a shapewhich fits in a standard milk crate.
 14. The method of claim 9 whereinthe blow molded container has a fill percentage of greater than about64%.
 15. A method for forming a blow-molded container comprising:providing a two or more piece mold including: a bottom section forforming a container bottom, sidewall section having a plurality ofsidewall surfaces for forming a plurality of long sidewalls, a pluralityof short sidewalls, and a sidewall upper limit, each long sidewall ofthe plurality of long sidewalls being substantially planar, theplurality of long sidewalls including a first pair of opposing parallelsidewalls that is spaced apart by a first dimension, and a second pairof opposing parallel sidewalls that is spaced apart by the firstdimension, each short sidewall from the plurality of short sidewallsbeing disposed between an adjacent pair of long sidewalls from theplurality of long sidewalls, the plurality of short sidewalls includinga third pair of sidewalls that is spaced apart by a second dimensionthat is different than the first dimension, and the sidewall upper limitextending along one or more long sidewalls from the plurality of longsidewalls and one or more short sidewalls from the plurality of shortsidewalls, a spout section for forming a spout, a neck section forforming an upwardly converging neck member coupling the sidewalls to thespout having a convex radius transition that is formed between thesidewall upper limit and the spout, wherein the convex radius transitiondefines a constant radius that extends continuously from the sidewallupper limit to the spout to provide a smooth transition between thesidewall upper limit and the spout, a die having an opening, and ahollow mandrel positioned within the opening of the die to define anannular opening between the opening of the die and the mandrel has anangle of about 15°-18°; forming a parison by introducing a thermoplasticmaterial in liquefied form through the opening between the die and themandrel; moving said mold pieces to a closed position proximate to thedie so the parison assumes an ovoid cross-section whereby each sidewallfrom the plurality of sidewalls of the mold is disposed at a similardistance from an outer surface of the parison; and inflating saidparison thereby bringing said parison into contact with said mold toform a container.
 16. A method for forming a blow molded container, saidcontainer having a length dimension and a width dimension less than saidlength dimension, the method comprising: providing a split mold havingan internal cavity having said length dimension and said width dimensionand a central vertical axis defining a midpoint in said length dimensionand said width dimension; positioning a circular die proximate to saidmold such that a radial center of said circular die is positionedco-axially with said vertical axis; positioning a circular, hollowmandrel having a central axis positioned co-axially with said die andsaid vertical axis; spacing said mandrel from said die to create anannular aperture between said die and said mandrel, wherein the annularaperture widens at an angle of about 15°-18° in relation to said axisfrom a narrow end of said annular aperture distal to said internalcavity of said mold to a widened end of said annular aperture proximalto said internal cavity of said mold; extruding heated thermoplasticmaterial through said aperture to form a parison having a uniform wallthickness; and inflating said parison to expand said parison uniformlyand bring said parison into contact with said mold to form a containerof uniform wall thickness.
 17. The method of claim 16, furthercomprising: causing said parison to assume an ovoid cross-section,whereby an outer surface of parison is positioned approximatelyequidistant from a plurality of sidewall surfaces of said mold prior toinflating said parison.